The present invention relates to the field of industrial material handling equipment, and more particularly but not by way of limitation, to an improved prefeeder assembly for feeding blanks and the like to processing equipment.
In the corrugated board industry certain finishing machines are used for the printing and folding of corrugated paper boxes. Such finishing machines can run small and medium sized boxes at high speeds. The collapsed boxes, referred to as blanks, flat boards or flats, can have edge length dimensions as small as about seven by twelve inches and as large as about thirty by seventy-two inches, or even larger. Stacks of large blanks can be as high as six feet and are delivered to a finishing machine for processing; in the case of smaller blanks, the stack height is usually decreased for stability reasons. Most of the finishing machines that are commercially available require the that the blanks be inverted before the blanks are fed into the machine. Once the process is started there can be no interruption in the feed rate of blanks because the quality of the finished box is adversely affected.
When large stacks of blanks are delivered to the finishing machine the blanks must be unstacked and an operator must manually provide handfuls of blanks into the feed hopper of the finishing machine. At the top speed of most finishing machines it is very difficult for operators to manually perform this task throughout a whole work shift. Further, it is quite usual for the finishing machine operation to require that the blanks must be inverted prior to feeding them to the finishing machines, which increases the manual work for the operator.
While prefeeder assemblies are known in the prior art, such prefeeder assemblies can not be operated at high rates of speed, and additionally, prior art prefeeders have problems handling very small blanks throughout the process.
In one type of prior art prefeeding machine, a stack of blanks is conveyed to an inverter where the stack is turned upside down and the blanks are passed from the bottom of the stack to the finishing machine. Another type of prior art prefeeding machine passes a stack of blanks to an elevator which indexes the stack upward, and an overhead pusher mechanism pushes discreet bundles from the top of the stack. The bundles are conveyed in sequence to a bundle inverter which turns each bundle upside down and conveys the inverted bundles to a finishing machine.
While prior art prefeeders may achieve the utility under discussion, there is a need for an improved prefeeder assembly which is capable of handling a range of blank sizes, especially smaller sizes, in an improved manner and with increased speed to overcome the limitations of the known prior art devices.
The improved prefeeder assembly of the present invention receives a stack of blanks for inverting and passing the inverted blanks to downstream processing equipment. The prefeeder assembly has a rotator frame which is positionable in an upright load entry position and in an inverted bundle discharge position, and a rotator frame actuator assembly supports the rotator frame and rotates the rotator frame between its upright load entry position and its inverted bundle discharge position. A rotator infeed conveyor is provided in the rotator frame to receive the stack of blanks when the rotator frame is in the upright load entry position. A lift platform assembly is also disposed in the rotator frame to clamp the stack on the rotator infeed conveyor during rotation of the rotator frame by the rotator frame actuator assembly.
A backstop and pusher assembly in the rotator frame includes a moveable backstop and a pusher member, the pusher member pushing a selective height of the blanks as a bundle from the stack when the rotator frame is rotated to the inverted bundle discharge position.
Blank bundles pushed from the stack at the inverted bundle discharge position are received by a centering conveyor which centers the blank bundles for delivery to processing equipment on an extendible conveyor. If desired, a shingling station can be provided after the centering conveyor, and tampering means can be provided to straighten the blanks prior to feeding same to processing equipment, such as a finishing machine.
The rotator frame actuator assembly also preferably serves to move the rotator frame along a horizontal path so that the rotator frame is in clearing relationship to other components and the incoming stack of blanks when it is rotated.
The objects, advantages and features of the present invention will be made clear from the following description when read in conjunction with the accompanying drawings.